core/modules/HashedString.cppm

module;

#include <cstdio>
#include <cstring>

export module Core.HashedString;

export import Core.Types;

export namespace Core {
    struct StringHash {
        size_t length = 0;
        size_t hash = 0;
    };

    constexpr StringHash hashString(const char* s) {
        StringHash h;
        while(*s != '\0') {
            h.length++;
            h.hash = 2'120'251'889lu * h.hash + static_cast<size_t>(*(s++));
        }
        return h;
    }

    template<size_t N>
    class HashedString {
        StringHash hash;
        char data[N];

    public:
        HashedString() : hash(), data{} {
        }

        HashedString(const char* s) : hash(hashString(s)) {
            snprintf(data, N, "%s", s);
        }

        bool operator==(const HashedString& other) const {
            return hash.length == other.hash.length &&
                   hash.hash == other.hash.hash &&
                   strcmp(data, other.data) == 0;
        }

        bool operator!=(const HashedString& other) const {
            return !(*this == other);
        }

        size_t getLength() const {
            return hash.length;
        }

        constexpr size_t getCapacity() const {
            return N - 1;
        }

        size_t hashCode() const {
            return hash.hash;
        }

        operator const char*() const {
            return data;
        }
    };
}